Benign partial epilepsy in infancy and early childhood with vertex spikes and waves during sleep: a new epileptic form

Recognition of interictal and ictal discharges on EEG. Focal vs generalized epilepsy

INTRODUCTION

The differentiation between focal and generalized epilepsies based on clinical and electroencephalographic features is difficult and sometimes confusing.

OBJECTIVE

To review the EEG findings in patients with focal epilepsy.

METHODS

An extensive literature review was done. We used the following Pubmed and Medline descriptors alone and in different combinations for database searching: focal, partial, epilepsy, electroencephalographic findings, and EEG. Additional filters included review, original articles, and language limited to Spanish and English. Using the above criteria, a total of 69 articles showed the interictal and ictal EEG findings in focal epilepsy.

DEVELOPMENT

Focal epileptiform discharges and persistence of focal abnormalities, characterize the interictal EEG findings in focal epilepsies. To distinguish SBS from primary generalized spike waves are required to note: (a) a lead-in time of at least 2 s, (b) the morphology of the focal triggering spikes clearly differ from that of the bisynchronous epileptiform paroxysms, and (c) the morphology of triggering spikes resemble that of other focal spikes from the same region. Focal and Generalized Epilepsy can coexist. Delayed Lateralization on EEG with inconclusive onset and bizarre semiology confusing semiology should not be confused with generalized onset seizures with focal evolution.

CONCLUSIONS

A close attention to localization and morphology of epileptiform discharges, the correct interpretation of secondary bilateral synchrony, and provocative maneuvers help to correctly identify the EEG findings leading to diagnose focal epilepsies. The presence of generalized epileptiform activity does not rule out the existence of a focal epilepsy.

Difficulty of Early Diagnosis and Requirement of Long-Term Follow-Up in Benign Infantile Seizures

PURPOSE

We investigated whether benign infantile seizures can be diagnosed in the acute phase.

METHODS

We retrospectively analyzed the medical records of 44 patients initially diagnosed with acute phase benign infantile seizures. All patients were followed for more than 12 months, and we reviewed patients' psychomotor development and presence or absence of seizure recurrence at the last visit. Patients were divided into the following three groups according to the final diagnosis: benign infantile seizures, benign infantile seizures associated with mild gastroenteritis, and non-benign infantile seizures. We defined benign infantile seizures associated with mild gastroenteritis and benign infantile seizures as those associated with normal psychomotor development and no seizure recurrence 3 months after onset of the first seizure, whereas non-benign infantile seizures were associated with delayed psychomotor development and/or seizure recurrence after 3 months of onset of the first seizure. We analyzed the clinical features in the acute phase and compared them between the groups.

RESULTS

The median age of seizure onset was 7.6 months. A final diagnosis of benign infantile seizures associated with mild gastroenteritis was made in three patients. In the remaining 41 patients, the final diagnosis was benign infantile seizures in 30 (73.2%) and non-benign infantile seizures in 11 (26.8%). In the non-benign infantile seizure group, intellectual disability was diagnosed in eight patients and seizure recurrence in six. There were no significant differences in clinical features between the groups in the acute phase, such as seizure type or seizure duration.

CONCLUSION

About 30% of patients initially diagnosed as having benign infantile seizures did not experience a benign clinical course. Our findings suggest that clinical features in the acute phase are not helpful for predicting benign outcomes in benign infantile seizures and that only long-term follow-up can discriminate benign infantile seizures from non-benign infantile seizures.

Asymptomatic viral gastrointestinal infection: the missing link?

We present the case of an 8-month-old boy who presented with apparent life-threatening events later characterized as seizures in clusters. A total of 14 apneic episodes were observed within 24 hours before loading the patient with phenobarbital at which point the seizures stopped. There was no obvious explanation for his seizures. EEG revealed midline interictal discharges; MRI-head was normal; and all other investigations were normal. The patient's stool was sent for virology with the clinical suspicion of benign infantile seizures associated with mild gastroenteritis (BISMG) despite lack of gastrointestinal symptoms. A small round virus was found. His clinical course followed the same progression as typical BISMG. This begs the question whether it is possible for virus in the stool to cause an asymptomatic gastrointestinal infection with its only clinical manifestation as seizures. We conclude that it may be possible for BISMG to present without gastrointestinal symptoms. As well, BISMG may be an unrecognized cause of apparent life-threatening events and should be considered in the differential diagnosis.

Idiopathic focal epilepsies

In this chapter we include a series of epilepsies with onset in pediatric age characterized by focal seizures, idiopathic etiology, normal psychomotor development, and a benign course related to the spontaneous remission of seizures without sequelae. These entities are age-dependent and seizures tend to disappear spontaneously. For these reasons often the drug treatment is not necessary. On the basis of genetic assessment idiopathic focal epilepsies can be divided into two groups: nonautosomal dominant and autosomal dominant. In the group of nonautosomal entities we include benign epilepsy with centro-temporal spikes, Panayiotopoulos syndrome, idiopathic childhood occipital epilepsy described by Gastaut, and benign idiopathic midline spikes epilepsy. Seizures are rare, sometimes prolonged, as autonomic status in Panayiotopoulos syndrome. A common feature is the presence of peculiar EEG interictal paroxysmal abnormalities. In the group with an autosomal dominant mode of inheritance we include benign familial infantile seizures and benign familial neonatal-infantile seizures. These entities are characterized by partial seizures in cluster, self-limited in a brief period during the first months of life. There are no typical interictal EEG abnormalities. In some families a mutation in SCN2A, the gene coding for the 2α subunit of the voltage-gated sodium channel, has been described.

Sleep spindle abnormalities in children with generalized spike-wave discharges

This study investigated sleep and sleep spindle parameters in children with primary generalized spike-and-wave discharges (untreated primary generalized group, nine patients; treated primary generalized group, six patients) and compared these with an age- and sex-matched nonepileptic control group (n = 47). In the untreated primary generalized group, stage 2 onset was significantly shorter, with less spindles in stage 2. In the last stage 2 period of the night, significantly less fast frequency spindles were observed, indicating abnormal dynamics of sleep architecture. In the treated group, sleep patterns were comparable to that of the control group. The data indicate sleep architecture dysfunctions in children with generalized spike-and-wave discharges. These dysfunctions could account for the frequently encountered sleep problems in children with primary generalized epilepsy.

The spectrum of benign infantile seizures

Benign epilepsies during infancy are a wide topic, which needs both clinical and nosological clarifications. Already in 1963 Fukuyama reported patients with seizures during infancy with a benign outcome. In the late 80s and early 90s, Watanabe reported series of infants with complex partial seizures or partial seizures with secondary generalization, with a normal development before onset and a benign outcome. In the same years Vigevano focused on familial cases: he described several families with seizures with onset around the 6-month of age, and autosomal dominant mode of inheritance. To define this condition, he coined the term "benign familial infantile seizures" (BFIS). Afterwards, studying families with this phenotype, loci on chromosomes 19, 16 and 2 responsible for BFIS were detected. Similar loci were found in families affected by BFIS and subsequent choreoathetosis, and BFIS associated with familial hemiplegic migraine. In most recent years a new form of benign epilepsy has been proposed, with an intermediate onset between the neonatal and infantile age, which was defined with the term benign familial neonatal-infantile seizures (BFNIS). This condition could have some clinical and genetic features overlapping with BFIS. Seizures with a benign outcome have been reported also in infants during episode of mild gastroenteritis (BIS with MG) frequently with positive Rotavirus antigen. Lastly, sleep EEG abnormalities have been reported in children with a peculiar form of epilepsy by Capovilla, who defined this condition as benign infantile focal epilepsy with midline spikes and waves during sleep (BIMSE). Some of these entities have been included in the last classification proposed by the ILAE and have been differentiated in familial and non-familial forms. The aim of this review is to describe these entities, discuss their nosological aspects, pointing out the similarities and differences with benign neonatal seizures and benign focal epilepsies appearing later in life such as early-onset benign occipital seizure susceptibility syndrome (EBOSS), or benign epilepsy of childhood with centro-temporal spikes (BECTS).

Classification of benign infantile afebrile seizures

PURPOSE

The aim of this study is to classify infantile cases with benign seizures into known epileptic syndromes, thereby facilitating discussion of clinical factors that could play an important role in diagnosis.

SUBJECTS

Fifty-seven patients with afebrile seizures fulfilling all of the following criteria were enrolled: (1) normal development prior to the onset, (2) no underlying disorders nor neurological abnormalities, (3) onset before the age of four and (4) normal interictal EEG and neuroimaging findings.

RESULTS

Thirty-nine cases (Group A) were characterized by an association of mild gastroenteritis. The remaining 18 cases were divided into two groups according to the seizure type. One group had partial seizures (Group B, 13 cases) while the other was suspected to have generalized seizures (Group C, 5 cases). Age at onset was significantly higher for Group A (19.5 +/- 5.5 months) than Groups B (5.3 +/- 1.8 months) (p<0.001) and C (5.8 +/- 3.5 months) (p=0.038). Positive family history of seizure disorder, seizure cluster tendency, and the efficacy of lidocaine against seizure clusters were common in the three groups.

CONCLUSIONS

Features in Group A were consistent with benign convulsions with mild gastroenteritis (proposed by Morooka) [Morooka, K., 1982. Mild diarrhea and convulsions. Shonika 23, 134-137 (in Japanese)], those of Group B with benign partial epilepsy in infancy [Watanabe, K., Yamamoto, N., Negoro, T., Takaesu, E., Aso, K., Furune, S., Takahashi, I., 1987. Benign complex partial epilepsies in infancy. Pediatr. Neurol. 3, 208-211], and those of Group C with benign infantile convulsions [Fukuyama, Y., 1963. Borderland of epilepsy with special reference to febrile convulsions and so-called infantile convulsions. Seishin Igaku 5, 211-223 (in Japanese)]. The distinction between these syndromes depends upon age at onset, association with gastroenteritis, and ictal symptomatology. In our experience, however, it was not easy to catch seizure type accurately in clinical situations. As far as the results of ictal video-EEG monitoring ever carried out concern, focal initiation of parxysmal discharges was demonstrated in all cases, not only of BPEI but also of apparent generalized seizures examined without exception. These observations led the authors to conclude that the identity of BIC is dubious, most probably it will represent a subtype of BPEI.

Benign Partial Epilepsy in Infancy: Myth or Reality?

PURPOSE

Benign partial epilepsy in infancy (BPEI) was first described by Watanabe in 1987. The aim of this study is to describe a series of infants from the United States to characterize this entity further.

METHODS

Among patients with the diagnosis of epilepsy followed up at our institution between 2002 and 2004, those satisfying the criteria for BPEI were included in a retrospective study.

RESULTS

Sixteen (10.2%) of 150 patients with new onset of epilepsy younger than 2 years were identified. The mean age at seizure onset was 8 months. Four (25%) infants had a family history of benign seizures. All infants were neurologically and developmentally normal at the onset of seizures. The seizures occurred in clusters in 75% of patients, predominantly in wakefulness. The initial manifestation was behavioral arrest with staring (69%) and apnea with cyanosis or pallor (37.5%). These symptoms were followed by deviation of eyes or head or both (56%), mild clonic movements (31%), or increased limb tone (35%). Secondary generalization was noticed in 37.5% of patients. All infants had normal interictal EEGs and brain MRIs. Ictal EEGs disclosed electrographic seizures in 50% of patients (temporal origin in 62% and central in 38%). Fifteen (94%) patients were treated with AEDs with good response. The mean duration of treatment was 12.4 months. The final developmental assessment of all patients was normal.

CONCLUSIONS

We believe that BPEI exists as a unique entity and should be included in the differential diagnosis of epilepsies in infancy with partial origin.

'Benign focal epilepsy in infancy with vertex spikes and waves during sleep'. Delineation of the syndrome and recalling as 'benign infantile focal epilepsy with midline spikes and waves during sleep' (BIMSE)

PURPOSE

To better delineate the electroclinical features of infants who presented with focal seizures and typical midline sleep EEG abnormalities with a benign outcome. We discuss the significance of the typical EEG marker in non-epileptic patients.

METHODS

Patients were selected from a group of epileptic subjects with seizure onset less than 3 years we observed from 1st November 1990 and 31st December 2003. Inclusion criteria were the presence of typical sleep EEG marker and focal seizures with benign outcome. Cases with less than 18 month follow-up period were excluded from this study.

RESULTS

There were 19 patients (12 males, 7 females). Pre-, peri- and post-natal personal history was negative in all patients. Psychomotor development was normal, both before and after seizure onset. Neuroradiological investigations gave normal results. Seizure manifestations were typical, characterized by cyanosis, staring and rare lateralizing signs, of short duration. Age at onset was comprised between 4 and 30 months. The typical EEG marker, a spike followed by a bell-shaped slow-wave, localized in the midline regions, was present in all subjects only during sleep. All had a favorable outcome and the overwhelming majority of the patients were not treated.

CONCLUSIONS

Our patients have an homogeneous electroclinical picture to constitute a new epileptic syndrome not included in the ILAE classification. We propose to call it 'benign focal epilepsy in infancy with midline spikes and waves during sleep' (BIMSE).

Long-term Follow-up of Patients with Benign Partial Epilepsy in Infancy

PURPOSE

The aim of this study was to investigate the long-term outcome of children with benign partial epilepsy in infancy (BPEI).

METHODS

A telephone-interview survey using a structured questionnaire was conducted with patients who were diagnosed as having possible BPEI at age 2 years and who were 8 years or older at the time of the survey. The data from 39 of 48 patients were available. The median age at the time of the survey was 11.3 years; 18 boys and 21 girls were included.

RESULTS

Three patients had a recurrence of unprovoked seizure beyond age 2 years. Four patients had cognitive problems (mild mental retardation in three and Asperger syndrome in one). An association of paroxysmal kinesigenic choreoathetosis was observed in three patients, and another three had experienced seizures associated with mild gastroenteritis. Major behavioral problems were not recognized in any patients. Four patients were excluded from having definite BPEI at age 5 years, and another two were excluded for having definite BPEI at the last follow-up. Eventually, 33 of 39 patients were categorized as having definite BPEI beyond 8 years of age.

CONCLUSIONS

A large majority of patients diagnosed as possibly having BPEI at age 2 years did not have a recurrence of unprovoked seizures and cognitive problems beyond 8 years of age.

Opercular to interhemispheric source distribution of benign rolandic spikes of childhood

We evaluated the source distribution of benign rolandic spikes of childhood along and across the central sulcus in 15 patients, aged between 7 and 15 years, who suffered from seizure disorders. Previous routine EEG showed centrotemporal spikes, but none of them had major abnormalities on brain magnetic resonance imaging or neurological deficits. The equivalent current dipoles (ECDs) of the spikes measured by whole-head magnetoencephalography (MEG) were compared to the spike distributions detected by simultaneous scalp EEG according to the international 10-20 system. Locations and orientations of the MEG spikes corresponded to the EEG spike distribution as follows: superiorly oriented spike MEG dipoles in the opercular area corresponded to T3/4 negative peaks (8 spike groups in 6 patients); anteriorly oriented spike dipoles in the rolandic area corresponded to C3/4 or P3/4 negative peaks (17 spike groups in 13 patients); laterally oriented spike dipoles in the interhemispheric area corresponded to Cz/Pz negative peaks (4 spike groups in 3 patients); and others (4 spike groups in 4 patients). Rolandic spikes include three main types according to the ECD location from the opercular to the interhemispheric areas. The functional anatomy of benign rolandic spikes was correlated with partial seizure semiology. All three rolandic spike types can be explained by a precentral origin, assuming that the surface negative potential is continuous from the gyral to fissural cortices.

Benign familial infantile seizures

In recent years, numerous publications have reported localization-related epilepsy with onset during early infancy, idiopathic etiology and favourable outcome. In 1963, Fukuyama reported cases occurring in the first 2 years of life characterized by partial seizures, absence of etiologic factors and benign outcome. Watanabe studied the localization and semiology of seizures. Later Vigevano and coworkers directed attention to the presence of cases with a family history of convulsions with benign outcome during infancy, with autosomal dominant inheritance, suggesting the term 'benign infantile familial convulsions' (BIFC). Similar cases have been described by several authors confirming that this is a new syndrome. In the last ILAE proposal of Classification of Epilepsy Syndromes this entity is called benign familial infantile seizures. Benign infantile seizures are divided now into familial and non-familial forms, although the two forms can overlap. Genetic studies led to the identification of a marker on chromosome 19. This was not confirmed by later studies, and genetic heterogeneity was hypothesized. Recently Malacarne studying eight Italian families with BIFC mapped a novel locus on chromosome 2. In 1997, Szepetowski described the association between BIFC and a later occurrence of paroxysmal choreoathetosis. Following the identification of a specific marker on chromosome 16, this entity constitutes a variant of the familial forms, called infantile convulsions and choreoathetosis. The age at onset, the semeiology of the seizures and the genetic data distinguish the benign familial infantile seizures from the benign familial neonatal seizures. Recent data suggested that this type of epilepsy would be due to a channellopathy.

Benign familial infantile convulsions: linkage to chromosome 16p12-q12 in 14 families

PURPOSE

Benign familial infantile convulsions (BFIC) is a form of idiopathic epilepsy. It is characterized by clusters of afebrile seizures occurring around the sixth month of life. The disease has a benign course with a normal development and rare seizures in adulthood. Previous linkage analyses defined three susceptibility loci on chromosomes 19q12-q13.11, 16p12-q12, and 2q23-31. However, a responsible gene has not been identified. We studied linkage in 16 further BFIC families.

METHODS

We collected 16 BFIC families, without an additional paroxysmal movement disorder, of German, Turkish, or Japanese origin with two to eight affected individuals. Standard two-point linkage analysis was performed.

RESULTS

The clinical picture included a large variety of seizure semiologies ranging from paleness and cyanosis with altered consciousness to generalized tonic-clonic seizures. Interictal EEGs showed focal epileptiform discharges in six patients, and three ictal EEGs in three distinct patients revealed a focal seizure onset in different brain regions. In all analyzed families, we found no evidence for linkage to the BFIC loci on chromosomes 19q and 2q, as well as to the known loci for benign familial neonatal convulsions on chromosomes 8q and 20q. In 14 of the families, the chromosome 16 locus could be confirmed with a cumulative maximum two-point lod score of 6.1 at marker D16S411, and the known region for BFIC could be narrowed to 22.5 Mbp between markers D16S690 and D16S3136.

CONCLUSIONS

Our data confirm the importance of the chromosome 16 locus for BFIC and may narrow the relevant interval.

Prognosis after withdrawal of antiepileptic drugs in childhood-onset cryptogenic localization-related epilepsies

The purpose of this study was to clarify the risk factors of relapse following discontinuation of AEDs in patients with childhood-onset cryptogenic localization-related epilepsies. The subjects were 82 patients who fulfilled the following criteria: (1) age at first visit of less than 15 years, (2) follow-up period of more than 5 years, (3) suffering from cryptogenic localization-related epilepsies, and (4) the patient underwent AED withdrawal during the follow-up period. As a basic principle, we decided to start withdrawing AEDs when both of the following two conditions were met: (1) the patient had a seizure-free period of 3 years or more, and (2) there were no epileptic discharges on EEGs just prior to the start of withdrawal. Seizures recurred in eight of the 82 patients (9.8%). Univariate analysis revealed that the following factors were correlated with higher rates of seizure relapse: 6 years of age or higher at onset of epilepsy; 15 years of age or higher at the start of AED withdrawal; 5 years or more from the start of AED treatment to seizure control; five or more seizures before seizure control; and two or more AEDs administered before seizure control. Among these risk factors, 6 years of age or higher at onset and 5 years or more from the start of AED treatment to seizure control were determined by multivariate analysis to be independent risk factors for relapse. Thus, we conclude that the physician should be more careful in discontinuing AEDs in these higher-risk patients groups, and more generous in discontinuing AEDs in lower-risk groups.

Search for alpha4 and alpha7 nicotinic acetylcholine receptor markers in a pedigree of benign familial infantile convulsions (BFIC)

In this study we investigate the possible involvement of the recently reported locus for benign familial infantile convulsions (BFIC) in human chromosome 19 and that of the neuronal acetylcholine receptor alpha4 (CHRNA4) and alpha7 (CHRNA7) subunits in a family with at least twelve clinically diagnosed cases of BFIC. Six polymorphic microsatellite markers covering the BFIC locus on chromosomal region 19q, one marker for CHRNA4 (chromosome 20) and two for CHRNA7 (chromosome 15) were used for the screening. The two-point lod score analysis showed no evidence of BFIC phenotype on chromosome 19. Similarly, when markers for chromosome 20 (CHRNA4 intron1, Amplimer: CHRNA4. PCR.1) and chromosome 15 (D15S165 and D15S1010) were used, score analysis showed no indication of linkage. The most likely interpretation of these results is that BFIC is a genetically heterogeneous form of epilepsy.

Benign partial epilepsies of adolescence: a report of 37 new cases

PURPOSE

To delineate the electroclinical features of patients with partial seizures in adolescence with a benign outcome.

METHODS

Patients were recruited in five different Italian epilepsy centers. Patients were selected among those with partial seizures between ages 11 and 17 years. We excluded benign childhood epilepsies, those with neurologic or mental deficits, and those with neuroradiologically documented lesions. We also excluded patients with less than 3 years' follow-up or who were still receiving antiepileptic therapy.

RESULTS

There were 37 (22 male, 15 female) patients. Seizures started at the mean age of 14.5 years (range, 11-16.11). Two main electroclinical patterns emerged: 16 of 37 patients had somatomotor seizures frequently associated with focal theta discharges involving the centroparietal regions. Ten of 37 patients showed versive seizures and interictal spiking involving the posterior regions. A third group had clinical characteristics resembling the cases described by Loiseau. All had a favorable outcome.

CONCLUSIONS

This relevant multicenter study further confirms the existence of benign partial epilepsies with onset during adolescence.

Benign idiopathic partial epilepsies in infancy

In infancy, partial epilepsies have been considered with suspicion for their probable association with brain lesions. Japanese authors first described partial epilepsies in infancy with a favorable outcome and called them benign partial epilepsy in infancy with complex partial seizures. Similar, but familial, cases with onset during the first year of life were described some years later and called benign infantile familial convulsions. Similar familial cases with subsequent choreoathetosis were described in 1997 and called infantile convulsions and choreoathetosis. Benign infantile convulsions have also been described in association with mild gastroenteritis. Interictal electroencephalography (EEG) was always normal in all of these forms. More recently, a new epileptic syndrome characterized by partial seizures with onset between ages 13 and 30 months, a benign outcome, and characteristic EEG abnormalities in the vertex regions during sleep has been described. There is also an early-onset benign childhood occipital seizure susceptibility syndrome that can start in infancy.